1. Field of the Invention
The present invention relates to a microprocessor having a processor core.
2. Description of the Related Art
According to a conventionally known technique, an embedded debugger interface is provided in a microprocessor and connected to a debugger, to allow an analysis of an internal condition of the processor to facilitate debugging at software development.
According to the conventional technique, the user can access from the debugger to resources such as a register and a memory inside the processor via the debugger interface embedded in the processor. In addition, the user can make the processor perform a stepwise execution.
The built-in debugger interface, however, facilitates not only the program verification by a legitimate software developer but also the software analysis by other software developers and users.
For example, if developed software contains confidential information, protection is necessary against analysis by software users as well as other software developers.
To this end, Japanese Patent Application Laid-Open No. 2002-244757, for example, proposes a method to disable a debugging function with use of a key selected at decryption, a method to disable a debugging operation when a protected program stored in a memory of the processor is selected as a debug target.
In some cases, however, a protected program and a non-protected program exist together. Then, an access from the debugger should be disabled only for the protected programs. Thus, there is a growing demand for a microprocessor which allows a flexible program protection.